Early-Phase Offshore Hydrocarbon Field Planning Considering Environmental Factors and Using Integrated Asset Modeling
Abstract This work discusses methods to quantify environmental indicators of development alternatives during the early design phase of offshore fields and how to include them in the selection process. The goal is to develop a decision-support method to: 1) evaluate field development alternatives of reduced environmental impact and 2) dealing with conflicting indicators such as economic value and environmental performance. A value chain model of a synthetic field located in the Norwegian Continental Shelf (NCS) was created using an integrated asset modeling tool. The model computes the net present value (NPV) of the project and the amount of CO2 emissions based on the hydrocarbon production profile and the field energy consumption. Several cases and field development power supply alternatives such as open-cycle gas turbine (OCGT), combined-cycle gas turbine (CCGT), power from shore and offshore wind farms are analyzed. It has been assumed that the gas turbine generates most of the CO2 and that the amounts of CO2 produced is a function of the field power consumption. The effect of the CO2 tax is included and studied. Results show that there are development alternatives that provide fair economic value while having low CO2 emissions. For the cases studied, the solutions with gas turbines have higher economic value than the solutions with power from shore and offshore wind farms, but emit large amounts of CO2. For solutions using gas turbine, a combined-cycle has less CO2 emission intensity (kgCO2/boe) than open-cycle, however, the energy intensity (kWh/boe) depended mainly on the amount of gas recycled and is highest for 75%. These indicators could allow field planners to evaluate and compare different field development concepts. Breakeven values of CO2 tax were determined for which the economic value of development with the gas turbine is equal to that of development with power from shore or offshore wind farms.